public ArrayList<String> BFS(String origin, String dest) {

        Queue<CityNode> queue = new LinkedList<CityNode>();

        Map<CityNode, CityNode> nodes = new HashMap<>();


        CityNode cityOrigin = cities.get(origin);
        CityNode cityDest = cities.get(dest);
        ArrayList<CityNode> visitedCities = new ArrayList<CityNode>();


        queue.offer(cityOrigin);
        nodes.put(cityOrigin, null);
        visitedCities.add(cityOrigin);
        boolean found = false;
        while (!queue.isEmpty()) {

            CityNode node = queue.poll();


            if (node == cityDest) {
                found = true;
                break;
            }


            for (int i = 0; i < node.connected.size(); i++) {
                CityNode c = node.connected.get(i);
                if (!visitedCities.contains(c)) {
                    queue.offer(c);
                    visitedCities.add(c);
                    nodes.put(c, node);
                }
            }
        }


        if (found) {

            ArrayList<String> path = new ArrayList<String>();
            CityNode curr = cityDest;
            while (curr != null) {
                path.add(0, curr.name);
                curr = nodes.get(curr); //This returns the predecessor of the current CityNode
            }
            return path;
        } else
            return null;
    }